TRANSACTIONS OF THE SECTIONS. 35 
to be formed about the 30th parallel of north latitude for the northern 
temperate zone, those which originate between two hours east and two 
hours west longitude as the sun traverses this portion of the torrid zone, 
and are directed towards England, will reach London between the S.E. 
and S.W. points, the S.E. and S. currents arriving first ; these will be 
succeeded by the S.W., and as the sun passes on in his progress the 
currents arrive at London with a more westerly direction, and those 
originating between four and five hours west, which are nearly S.W. at 
the 30th parallel, beegme W. at London. In this manner the currents 
vary, following the course of the sun, until he arrives at the 10th meri- 
dian west of Greenwich; the current produced here reaches London as 
a N.W. wind, while that moving towards the north in longitude 180° 
arrives at London as a N. wind. As the currents produced at places si- 
tuated more and more westerly of 180° arrive, they acquire a more 
easterly character, until the sun reaches between five and four hours 
east, when the direction of the wind becomes east, the N.E. originating 
at ten hours east, as the N.W. originated at ten hours west; the wind 
then progresses to S.E., and the same order recommences. 
The above account of the formation of currents on the equatorial 
boundaries of the temperate zones the author supposes will sufficiently 
explain the progression of the wind round the compass in a direct order ; 
and in consequence of the large space which the currents (that are 
formed near the opposite meridian) have to traverse, compared with that 
which the southern currents pass over, the greater prevalence of S.W. 
winds is readily accounted for. England, however, from its position 
in the north temperate zone, is subjected to the influence of those cur- 
rents that proceed from the pole towards the equator to supply the place 
_ of the air which ascends by the heating power of the sun ; these currents 
arrive at London from all points between W. and E. towards N. in the 
order W., N., E. and may concur in their arrival with the N.W.,N. and 
N.E. equatorial currents, or the S.E., S., and S.W., producing a diversity 
of phenomena according as they are situated W. or E. of them. If for 
instance a N.W. polar current arrives with a N. equatorial, the resultant 
wind is N.N.W.; and if the equatorials have steadily proceeded from 
S.E. to N., in consequence of the position of the two kinds of currents, 
a regression will take place, which will be greater the further the winds 
are from each other: this state of things will considerably influence the 
remaining winds which, combined with the meeting of differently posited 
equatorial currents, may induce a permanent regression of a greater or 
Jess magnitude, and which gives place to a direct order, upon the polar 
currents preceding the equatorial in their arrival. These views, the 
author conceives, will sufficiently explain the variations exhibited in his 
_ diagram, which suggests the idea, that the revolutions of the equatorial 
_ and polar currents are extremely regular, and that the antecedence and 
consequence of the polar relative to the equatorial currents are subject 
to laws capable of being ascertained by careful observation. During 
the first half of the period tabulated, there were two alternations of 
the equatorial and polar, and during the latter half the same alterna- 
_ tions occurred in a reverse order. 
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